Welcome to the Hubitat community!
The connection issue may be related to the Hue Bulbs. They will try to repeat the Zigbee signals, as that’s how Zigbee works, but while they happily repeat the signals for bulbs on HE, they do a terrible job of repeating the signal for other devices.
You will have very stable performance by adding a Hue bridge, add the lights to the bridge and control them via the Hue Integration app in HE. The Motion Sensors will be fine to leave on HE if you want, but combining them with Hue bulbs on the same HE hub will cause the Zigbee mesh to become unstable.
If you don’t want to add a Hue Bridge, then you can return the Hue bulbs and instead buy Sengled bulbs. They are the only Zigbee bulbs know NOT to try to repeat the Zigbee signal.
If your home is large (and even if it’s not), you are going to want to add Zigbee repeaters for a stable Zigbee network. IKEA TRÅDFRI outlets and the dedicated TRÅDFRI signal repeater are inexpensive and work well over moderate distances.
Here’s a document that will help
https://docs.hubitat.com/index.php?title=How_to_Build_a_Solid_Zigbee_Mesh
In regard to the Wi-Fi devices, there are some that are officially supported, but most that work or community drivers and not supported by Hubitat staff. There is a particular way to control Wi-Fi devices that are supported by Google Assistant, but it is a bit advanced if you’re just starting out. This method to his community created and not supported by Hubitat staff. however it works really well and I use it myself also. Currently it’s only downside is getting status back from the device is a bit difficult. One of the community members is actually working on something that might make that easier
